Preheat oven to 180C/160C fan forced. Line a baking tray with baking paper.
For the dressing, place the tomato, cut-side down, on prepared tray. Drizzle with 2 tsp oil. Season. Roast for 25 minutes or until tender. Transfer to a sieve set over a bowl. Use the back of a spoon to push through the sieve to extract juice. Discard solids. Combine the lime juice, vinegar, sugar, 1/3 cup tomato puree and remaining oil in a bowl. Season well. Reserve 1/4 cup of the dressing.
Finely chop 2 /3 cup of the fresh herbs. Combine the chopped herbs, rind, garlic and reserved dressing in a bowl. Combine the squid and oil in a separate bowl. Season.
Preheat a barbecue or chargrill on medium-high. Cook the squid, turning, for 2 minutes or until just cooked through. Add to the herb mixture. Toss to coat.
Combine the celery, celery leaves, onion, tomato, radishes, prawns, squid mixture, remaining herbs and half the dressing in a bowl. Toss to combine. Transfer to a plate. Serve with remaining dressing on the side.
